Phase change memory cell with a thermal barrier layer

Abstract

A method may include forming a bottom electrode in an interlayer dielectric, depositing a liner on top of the bottom electrode, depositing a phase change material layer on top of the liner, wherein a top surface of the liner is in direct contact with a bottom surface of the phase change material layer, and depositing a barrier on top of the phase change material layer, wherein a top surface of the phase change material layer is in direct contact with a bottom surface of the barrier. The barrier may be made of doped phase change material. The forming of the bottom electrode may further include forming a via in the interlayer dielectric, depositing an outer layer along a bottom and a sidewall of the via, depositing a middle layer on top of the outer layer, and depositing an inner layer on top of the middle layer.

What is claimed is: 
     
       1. A structure comprising:
 a bottom electrode; 
 a phase change material layer on top of the bottom electrode; 
 a liner between and in direct contact with the bottom electrode and the phase change material layer, wherein the liner is configured to provide a current shunt path around an amorphous portion of the phase change material layer to a crystalline portion of the phase change material layer; and 
 a barrier on top of the phase change material layer, wherein the barrier directly contacts and separates the phase change material layer from a top electrode, wherein the barrier is made of a phase change material that is doped with one or more dopants and that differs from a material from which the liner is formed. 
 
     
     
       2. The structure of  claim 1 , wherein the bottom electrode comprises:
 an outer layer; 
 a middle layer, wherein the middle layer is between the outer layer and an inner layer; and 
 the inner layer, wherein the inner layer is surrounded by the middle layer. 
 
     
     
       3. The structure of  claim 2 , wherein the outer layer is less conductive than the middle layer. 
     
     
       4. The structure of  claim 2 , wherein the middle layer is more conductive than the inner layer. 
     
     
       5. The structure of  claim 1 , wherein the liner separates the bottom electrode from the phase change material layer. 
     
     
       6. The structure of  claim 1 , wherein the phase change material layer and the barrier have different thermal conductivities. 
     
     
       7. The structure of  claim 1 , wherein the phase change material is a mixture of a mixture of gallium, antimony, and at least one material selected from the group consisting of tellurium, silicon, germanium, arsenic, selenium, indium, tin, bismuth, silver, gold, and additional antimony. 
     
     
       8. The structure of  claim 1 , wherein the phase change material is a chalcogenide alloy selected from the group consisting of germanium-antimony-tellurium, antimony-tellurium, antimony, and germanium-tellurium. 
     
     
       9. A structure comprising:
 a bottom electrode, the bottom electrode is cylindrical in shape; 
 a phase change material layer on top of the bottom electrode; 
 a liner separating the bottom electrode from the phase change material layer wherein the liner directly contacts the bottom electrode and the phase change material layer, and wherein the liner is configured to provide a current shunt path around an amorphous portion of the phase change material layer to a crystalline portion of the phase change material layer; and 
 a barrier on top of the phase change material layer, wherein the barrier directly contacts and separates the phase change material layer from a top electrode, wherein the barrier is made of a phase change material that is doped with one or more dopants and differs from a material from which the liner is formed. 
 
     
     
       10. The structure of  claim 9 , wherein the bottom electrode comprises:
 an outer layer; 
 a middle layer, wherein the middle layer is between the outer layer and an inner layer; and 
 the inner layer, wherein the inner layer is surrounded by the middle layer. 
 
     
     
       11. The structure of  claim 10 , wherein the outer layer is less conductive than the middle layer. 
     
     
       12. The structure of  claim 10 , wherein the middle layer is more conductive than the inner layer. 
     
     
       13. The structure of  claim 9 , wherein the phase change material layer and the barrier have different thermal conductivities. 
     
     
       14. The structure of  claim 9 , wherein the phase change material is a mixture of a mixture of gallium, antimony, and at least one material selected from the group consisting of tellurium, silicon, germanium, arsenic, selenium, indium, tin, bismuth, silver, gold, and additional antimony. 
     
     
       15. A structure comprising:
 a bottom electrode, wherein the bottom electrode is on top and in direct contact with a top surface of a wire; 
 a phase change material layer on top of the bottom electrode; 
 a liner separating the bottom electrode from the phase change material layer, the liner directly contacts the bottom electrode and the phase change material layer, and wherein the liner is configured to provide a current shunt path around an amorphous portion of the phase change material layer to a crystalline portion of the phase change material layer; and 
 a barrier on top of the phase change material layer, wherein the barrier directly contacts and separates the phase change material layer from a top electrode, wherein the barrier is made of a phase change material that is doped with one or more dopants and differs from a material from which the liner is formed, and wherein the barrier thermally insulates the top electrode from the phase change material layer. 
 
     
     
       16. The structure of  claim 15 , wherein the bottom electrode comprises:
 an outer layer; 
 a middle layer, wherein the middle layer is between the outer layer and an inner layer; and 
 the inner layer, wherein the inner layer is surrounded by the middle layer. 
 
     
     
       17. The structure of  claim 16 , wherein the outer layer is less conductive than the middle layer. 
     
     
       18. The structure of  claim 16 , wherein the middle layer is more conductive than the inner layer. 
     
     
       19. The structure of  claim 15 , wherein the phase change material layer and the barrier have different thermal conductivities. 
     
     
       20. The structure of  claim 15 , wherein the phase change material is a mixture of a mixture of gallium, antimony, and at least one material selected from the group consisting of tellurium, silicon, germanium, arsenic, selenium, indium, tin, bismuth, silver, gold, and additional antimony.